1. Field of the Invention
The present invention relates to an image processing apparatus connected to a printing apparatus which prints an image by discharging inks onto a printing medium according to image data, an image processing method, and a program and, more particularly, to an image processing apparatus having a plurality of different image data formats, an image processing method, and a program.
2. Description of the Related Art
In recent printing apparatus such as ink-jet printing apparatuses and the like, a printing time per page becomes dramatically shorter due to improved printing speeds. For this reason, printing data need to be transferred at high speed so as to speed up the overall printing processing. However, the data size of printing data is increasing due to higher-resolution and higher-quality images to be printed. For this reason, a printing apparatus has a high-speed interface such as USB (Universal Serial Bus) compatible to a High Speed mode, and the like. However, in some popular configurations, a printing apparatus is wirelessly connected using a low-speed interface such as Bluetooth™, IEEE802.11b, or the like in place of connecting the printing apparatus to a host computer by wire like the High Speed mode of USB. In another configuration, a host computer is connected to a printing apparatus via a low-speed interface such as a USB connection that is compatible to only a Full Speed mode, or the like, depending on the types of host computers.
Hence, as a method for shortening the transfer time of printing data even in the configuration using a low-speed interface, a method of determining a compression method of printing data based on the type of interface is available (see Japanese Patent Laid-Open No. 2005-215954). Also, a method of determining a compression method by dividing image data into a plurality of bands, and recognizing the type of image data in each band is available (see Japanese Patent Laid-Open No. H11-259243).
In general, a printing medium printed by an ink-jet printing apparatus is output before inks discharged on its printing medium surface dry, and is stacked on a paper output tray. In particular, upon printing using slow-fixing inks or printing media, when printing of the next page on a printing medium is immediately started, that printing medium is stacked on the paper output tray before the inks of the surface of a printing medium printed as the immediately preceding page dry. Hence, the printing medium printed as the next page may become tainted or an image printed on the printing medium of the previous page may become tainted. To solve this problem, a printing control apparatus which calculates an ink dry time of the printing medium printed as the immediately preceding page based on the type of printing medium, the type of inks, the ambient temperature, a printing mode, and the like, waits for the calculated ink dry time, and then starts a printing operation on the next printing medium is available (see Japanese Patent Laid-Open No. H11-348247).
A method of designating an ink dry time of a printed printing sheet, which is printed as the immediately preceding page, by a printer driver in a host computer connected to a printing apparatus is also available.
Furthermore, a printing control apparatus which periodically executes a maintenance function of a printing apparatus during printing processing so as to maintain high quality of printed images is available (see Japanese Patent Laid-Open No. 2003-241951).
In Japanese Patent Laid-Open No. 2005-215954 and Japanese Patent Laid-Open No. H11-259243 above, the printing processing time is shortened by reducing the size of printing data. However, as described in Japanese Patent Laid-Open No. H11-348247 above, when the printing apparatus waits for the ink dry time, printing data for the second and subsequent pages can be transmitted while the printing apparatus is waiting.
FIG. 3A is a timing chart showing an example in which printing data is transmitted while the printing apparatus is waiting for the ink dry time. A host computer 100 generates printing data by executing rasterize processing and compression processing. The host computer 100 then transmits the printing data to a printer 105. The printer 105 transmits a reception response to the received printing data to the host computer 100, and executes decompression processing of the received printing data. After that, the printer 105 executes printing processing.
Focusing on the operation after the decompression processing and printing processing for printing data of the first page, the printer 105 waits for the ink dry time (ink dry waiting) to let the ink on the printing medium of the first page dry. During this ink dry waiting, the printer 105 can receive printing data from the host computer 100. However, when the ink dry time is long, the printer 105 continues ink dry waiting by a time Td even after it has received all printing data of the second page, as shown in FIG. 3A.
For this reason, the case of FIG. 3A has no effect of shortening the time required for the printing processing of the second and subsequent pages even when the printing data transfer time is shortened by reducing the size of printing data. In addition, when lossy compression is used to reduce the size of printing data, there is no effect of shortening the time from the beginning to the end of the printing operation, and the quality of a printed image also drops.
A quality drop of a printed image is conspicuous when an image like a character having a sharp edge is printed on a printing medium. For example, an image processing apparatus which forms an image on a printing medium using dye and pigment inks may often suffer a quality drop of a printed image. More specifically, upon using lossless compression, a character part can be formed only pigment ink. However, upon using lossy compression, since image data after the decompression processing changes, a character may often be formed using dye ink. Since the dye ink permeates better into a printing medium than the pigment ink, a character using the dye ink suffers blurring on a printing medium compared to that formed using only the pigment ink. For this reason in particular, the quality of a character part formed using the dye ink drops.